Distribution - the process of the dispersion of the drug into the blood stream and tissues

Metabolism - the process of the parent compounding into daughter metabolites

Excretion - the process of eliminating the drug from the body

Dosage intervals

Zero order pharmacokinetics, the rate of reaction is independent of the concentration of the reactants:

r = k

Drugs following zero order pharmacokinetics; Mnemonic: 'Peas & WHEATS' (A Pea would look like a zero and denotes the order). Pea also stands for 'Pee'-ing out a constant amount as in zero order kinetics constant amount of the drug is eliminated per unit time. Rate of elimination is constant and does not depend on or vary with the drug intake or plasma concentration of the drug.

Drugs undergoing complete first pass metabolism when not taken orally: 'FILTHy'

First pass metabolism

Isoprenaline

Lignocaine (Lidocaine)

Testosterone

Hydrocortisone

Drugs metabolized by acetylation, acetylator polymorphism: Some individuals are slow acetylators and some are fast acetylators.The drugs metabolized by acetylation may become ineffective in fast acetylators and cause toxicity in slow acetylators. Mnemonic: 'SHIP'